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@@ -0,0 +1,92 @@
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+//
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+// helper.cxx
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+// graphics
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+//
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+// Created by Sam Jaffe on 5/18/19.
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+// Copyright © 2019 Sam Jaffe. All rights reserved.
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+//
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+
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+#include "helper.hpp"
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+
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+#ifdef __APPLE__
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+#include <OpenGL/gl3.h>
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+#endif
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+
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+#include "vector/vector.hpp"
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+
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+namespace graphics { namespace detail { namespace texture {
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+ static int glfmt(format color_fmt) {
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+ switch (color_fmt) {
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+ case format::RGB:
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+ return GL_RGB;
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+ case format::RGBA:
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+ return GL_RGBA;
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+ }
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+ }
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+
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+ unsigned int init(format color_fmt, math::vec2i dimension,
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+ unsigned char * data) {
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+ unsigned int id;
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+ // Enable texturings
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+ // glEnable( GL_TEXTURE_2D );
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+
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+ // Tell OpenGL that our pixel data is single-byte aligned
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+ glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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+
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+ // Ask OpenGL for an unused texName (ID number) to use for this texture
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+ glGenTextures(1, &id);
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+
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+ // Tell OpenGL to bind (set) this as the currently active texture
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+ glBindTexture(GL_TEXTURE_2D, id);
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+ // Set texture clamp vs. wrap (repeat)
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+
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+ // one of: GL_CLAMP_TO_EDGE, GL_REPEAT, GL_MIRRORED_REPEAT,
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+ // GL_MIRROR_CLAMP_TO_EDGE, ...
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+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
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+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
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+
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+ // the format our source pixel data is currently in; any of: GL_RGB,
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+ // GL_RGBA, GL_LUMINANCE, GL_LUMINANCE_ALPHA, ...
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+ int bufferFormat = glfmt(color_fmt);
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+
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+ // the format we want the texture to me on the card; allows us to translate
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+ // into a different texture format as we upload to OpenGL
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+ int internalFormat = bufferFormat;
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+
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+ /* glTexImage2D: Load a 2d texture image
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+ * target: Creating this as a 2d texture.
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+ * level: Which mipmap level to use as the "root" (0 = the highest-quality,
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+ * full-res image), if mipmaps are enabled.
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+ * internalFormat: Type of texel format we want OpenGL to use for this
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+ * texture internally on the video card.
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+ * width: Texel-width of image; for maximum compatibility, use 2^N + 2^B,
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+ * where N is some integer in the range [3,10], and B is the border
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+ * thickness [0,1]
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+ * height: Texel-height of image; for maximum compatibility, use 2^M + 2^B,
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+ * where M is some integer in the range [3,10], and B is the border
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+ * thickness [0,1]
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+ * border: Border size, in texels (must be 0 or 1)
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+ * format: Pixel format describing the composition of the pixel data in
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+ * buffer
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+ * type: Pixel color components are unsigned bytes (one byte per color/alpha
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+ * channel)
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+ * pixels: Location of the actual pixel data bytes/buffer
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+ */
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+ glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, dimension.x(), dimension.y(),
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+ 0, bufferFormat, GL_UNSIGNED_BYTE, data);
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+
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+ glGenerateMipmap(GL_TEXTURE_2D);
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+
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+ // Set magnification (texel > pixel) and minification (texel < pixel)
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+ // filters one of: GL_NEAREST, GL_LINEAR
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+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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+ // one of: GL_NEAREST, GL_LINEAR, GL_NEAREST_MIPMAP_NEAREST,
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+ // GL_NEAREST_MIPMAP_LINEAR, GL_LINEAR_MIPMAP_NEAREST,
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+ // GL_LINEAR_MIPMAP_LINEAR
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+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
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+ GL_NEAREST_MIPMAP_LINEAR);
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+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 5);
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+
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+ return id;
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+ }
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+}}}
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Sam Jaffe